KR20230088783A - Electrolyte, secondary battery including the same, and manufacturing method of the secondary battery - Google Patents

Abstract

This application provides an electrolyte solution, a secondary battery, a battery pack, and an electric device. The electrolyte solution includes an electrolyte salt having a molar concentration greater than or equal to 1.4 mol/L and an additive including MSO3F (fluorosulfonate), wherein M is a metal ion, and the metal ion includes Li+, Na+, K+, Rb+, At least one of Cs+ is selected. A specific manufacturing method of the secondary battery is to prepare an electrolyte solution having an electrolyte salt concentration greater than or equal to 1.4 mol/L, and to perform conversion by adding an additive.

Description

Electrolyte, secondary battery including the same, and manufacturing method of the secondary battery

This application claims the priority of Chinese Patent Application No. 202111131748.1, filed on September 26, 2021, entitled 'Electrolyte, secondary battery containing the same, and manufacturing method of the secondary battery', and the entire contents of the application are hereby incorporated by reference. included in the circle

This application relates to the technical field of a lithium battery, and in particular, to an electrolyte solution, a secondary battery including the same, and a method for manufacturing the secondary battery.

In recent years, as the scope of application of secondary batteries is gradually expanding, secondary batteries are applied not only to power systems for energy storage such as hydropower, thermal power, wind power and solar power plants, but also to power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, It is widely applied in various fields such as aerospace. With the tremendous development of secondary batteries, the requirements for energy density, cycle shelf life, etc. become higher.

The present application has been made in view of the above problems, and aims to provide a secondary battery having a better cycle shelf life and an electrolyte whose production efficiency is comparable to that of conventional electrolyte systems.

In order to achieve the above object, in the first aspect of the present application, in providing an electrolyte solution, the electrolyte solution includes an electrolyte salt and an additive, the concentration of the electrolyte salt is greater than or equal to 1.4 mol / L, and the additive is MSO F (fluoro sulfonate), wherein at least one of Li+, Na+, K+, Rb+, and Cs+ is selected as M.

The present application not only has a stable solvation structure by using an electrolyte with a high lithium salt concentration in combination with a fluorosulfonate additive, but also has excellent oxidation resistance and low oxidative decomposition at high voltage, so the cycle and storage performance of the battery is improved. improve effectively.

In certain embodiments, the concentration of the electrolyte salt is between 1.7 and 2.9 mol/L.

In certain embodiments, the electrolyte salt includes one or more of (My+)x/y R1(SO2N)xSO2R2, LiPF6, LiBF4, LiBOB, LiAsF6, LiCF3SO3, LiFSI, and LiClO4, wherein R1 and R2 are each independently a fluorine atom. , A fluoroalkyl group having 1 to 20 carbon atoms, a fluoroalkoxy group having 1 to 20 carbon atoms, or an alkyl group having 1 to 20 carbon atoms, and x is an integer of 1 to 3. In some embodiments, the electrolyte salt includes one or more of LiFSI, LiPF6, LiCF3SO2NSO2F.

In certain embodiments, the fluorosulfonate comprises one or more of LiSO3F, NaSO3F, KSO3F, RbSO3F, CsSO3F.

In an optional embodiment, the mass of the fluorosulfonate in the electrolyte solution is 0.1 to 5 wt%, optionally 0.2 wt% to 4 wt%.

In an optional embodiment, the additive further includes an organic compound film-forming additive and an inorganic salt film-forming additive, wherein the organic compound film-forming additive includes at least one of carbonic acid esters, sulfuric acid esters, sulfonic acid esters, phosphoric acid esters, boric acid esters, and anhydrides, The inorganic salt film forming additive includes at least one of fluorine oxalic acid borate, difluoro phosphate, difluoro bis(oxalate)phosphate, and difluoro bis oxalate.

In the second aspect of the present application, in providing a method for manufacturing a secondary battery, providing an electrolyte solution - the electrolyte solution includes an electrolyte salt and an additive, the concentration of the electrolyte salt is greater than or equal to 1.4 mol / L, and the additive is MSO3F Including, wherein M is at least one selected from Li+, Na+, K+, Rb+, and Cs+ -; and injecting the electrolyte solution into the battery.

In providing a secondary battery in the third aspect of the present application, a secondary battery manufactured using the electrolyte solution according to the first aspect of the present application or the manufacturing method according to the second aspect of the present application is included.

In providing a battery module in the fourth aspect of the present application, the secondary battery according to the third aspect of the present application is included.

In providing a battery pack in the fifth aspect of the present application, the battery module according to the fourth aspect of the present application is included.

In the sixth aspect of the present application, in providing an electric device, at least one of the secondary battery according to the third aspect of the present application, the battery module according to the fourth aspect of the present application, or the battery pack according to the fifth aspect of the present application include

Since the secondary battery of the present application includes the secondary battery manufactured using the electrolyte solution according to the first aspect of the present application and the manufacturing method according to the second aspect of the present application, it has excellent cycle storage performance.

Hereinafter, in order to more clearly describe the technical solution of the embodiment of the present application, drawings necessary for describing the embodiment of the present application will be briefly introduced. The drawings introduced below show only some of the embodiments of the present application, and it is clear that those skilled in the art can obtain other drawings based on these drawings without creative efforts.
1 is a schematic diagram of a secondary battery according to an exemplary embodiment of the present application.
2 is an exploded schematic diagram of a secondary battery according to an exemplary embodiment of the present application.
3 is a schematic diagram of a battery module according to an embodiment of the present application.
4 is a schematic diagram of a battery pack according to an exemplary embodiment of the present application.
5 is an exploded view of a battery pack according to an exemplary embodiment of the present application shown in FIG. 4 .
6 is a schematic diagram of an electric device using a secondary battery as a power source according to an exemplary embodiment of the present application.

Hereinafter, embodiments of a positive electrode plate, a negative electrode plate, a secondary battery, a battery module, a battery pack, and an electric device of the present application will be described in detail with appropriate reference to the accompanying drawings. However, there may be cases where unnecessary detailed descriptions are omitted. For example, detailed descriptions of well-known items or repeated descriptions of the same structure may be omitted. This is to avoid unnecessarily lengthening the following description and to aid understanding of those skilled in the art. In addition, the drawings and the following description are provided so that those skilled in the art can fully understand the present application, and are not intended to limit the subject matter described in the claims.

A 'range' as disclosed herein is defined in the form of a lower limit and an upper limit, where a given range is defined by a selection of lower and upper limits, and the selected lower and upper limits define the boundaries of the particular range. Ranges defined in this way may be inclusive or exclusive, and may be in any combination. That is, any lower limit may be combined with any upper limit to form a range. For example, if ranges of 60 to 120 and 80 to 110 are listed for a specific parameter, it can be understood that ranges of 60 to 110 and 80 to 120 are also expected. Also, if minimum range values of 1 and 2 and maximum range values of 3, 4, and 5 are listed, all ranges would be expected to be 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5. can In this application, unless otherwise specified, the numerical range 'a to b' represents an abbreviated expression of any combination of real numbers from a to b, where a and b are real numbers. For example, a numeric range of '0 to 5' indicates that all real numbers between '0 and 5' are listed here, and '0 to 5' is an abbreviated representation of this combination of numbers. In addition, when a specific parameter is expressed as an integer ≧2, it is the same as disclosing that the parameter is an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, and the like.

Unless otherwise specified, all implementations and optional implementations of the present application may be combined with each other to form a new technical solution.

Unless otherwise specified, all technical features and optional technical features of the present application may be combined with each other to form a new technical solution.

Unless otherwise specified, all steps in this application may be performed sequentially or randomly. For example, if a method includes steps (a) and (b), then the method includes steps (a) and (b) performed sequentially, or steps (b) and (a) performed sequentially. indicates that it includes For example, if the method described above further comprises step (c), it is indicated that step (c) may be added to the method in any order. For example, the method includes steps (a), (b) and (c), includes steps (a), (c) and (b), steps (c), (a) and (b), etc. can include

Unless otherwise specified, 'include' referred to in this application indicates an open or closed type. For example, the 'includes' may indicate that other components not listed are included or only the listed components are included.

Unless otherwise specified, in this application, the term 'or' is inclusive. For example, the phrase 'A or B' refers to 'A, B, or A and B'. More specifically, A is true (or present) and B is false (or absent); A is false (or absent) and B is true (or present); Any condition in which both A and B are true (or present) satisfies the condition 'A or B'.

[Secondary battery]

A secondary battery is also called a rechargeable battery or a storage battery, which means a battery that can be continuously used by activating an active material in a charging method after discharging the battery.

In general, a secondary battery includes a positive electrode plate, a negative electrode plate, a separator, and an electrolyte solution. During the charging and discharging process of the battery, active ions (eg, lithium ions) are intercalated and deintercalated between the positive and negative plates while reciprocating. The separator is disposed between the positive electrode plate and the negative electrode plate to prevent a short circuit between the positive electrode and the negative electrode and allow active ions to pass through. The electrolyte serves to conduct active ions between the positive and negative plates.

[Electrolyte]

Electrolyte is a bridge that allows active ions to pass through in a secondary battery, and plays a role in transporting active ions between positive and negative electrodes of a battery and plays an important role in rapid charging performance, specific capacity, cycle efficiency, and safety performance of a battery.

The present inventors found that the currently commonly used electrolyte is an electrolyte system composed of a conventional carbonate ester solution and LiPF6, and the lithium salt concentration is generally 0.6 to 1.3 mol/L, but this system is easily oxidized in a high voltage (>4.35V) system. It was found that decomposition affects the cycle and storage performance of the battery.

In order to solve the above technical problem, the present application provides an electrolyte solution, wherein the electrolyte solution includes an electrolyte salt and an additive, the concentration of the electrolyte salt is greater than or equal to 1.4 mol/L, and the additive is MSO3F (fluorosulfonate) Including, wherein M is selected from one or more of Li + , Na + , K + , Rb + , and Cs + .

Through many studies, the inventors have found that when the electrolyte satisfies the concentration of the electrolyte salt greater than or equal to 1.4 mol/L and at the same time uses a fluorosulfonate film forming additive in combination, the cycle and storage performance of the battery at high voltage can be effectively improved. found that there is According to the conjecture of the inventor, the concentration of the electrolyte salt reduces the content of the free solvent within the above range to stabilize the solvation structure, so that the electrolyte has relatively good oxidation resistance and less oxidative decomposition at high voltage, and at the same time, fluorosulfonate Through the combination and use of film forming additives, where the fluorosulfonic acid salt strengthens the film formation of the anode and cathode, effectively reduces the catalytic oxidation reaction of the electrolyte on the surface of the anode, and reduces the side reaction at the interface between the electrolyte and the cathode at high voltage, thereby improving the cycle of the battery. and storage performance can be effectively improved, and the lithium ion transport resistance can be reduced by accelerating the desolvation process of lithium ions.

In some implementations, the concentration of the electrolyte salt is 1.7-2.9 mol/L. When the concentration of the electrolyte salt is within an appropriate range, the stability of the solvation structure can be further improved, and thus the cycle and storage performance of the battery can be further improved.

In some embodiments, the electrolyte salt includes one or more of (My+)x/y R1(SO2N)xSO2R2, LiPF6, LiBF4, LiBOB, LiAsF6, LiCF3SO3, LiFSI and LiClO4, wherein R1 and R2 are each independently a fluorine atom; A fluoroalkyl group having 1 to 20 carbon atoms, a fluoroalkoxy group having 1 to 20 carbon atoms, or an alkyl group having 1 to 20 carbon atoms, and x is an integer of 1 to 3. In some embodiments, the electrolyte salt includes one or more of LiFSI, LiPF6, LiCF3SO2NSO2F.

In some embodiments, the fluorosulfonate additive includes one or more of LiSO3F, NaSO3F, KSO3F, RbSO3F, CsSO3F.

In some embodiments, the mass of the fluorosulfonate in the electrolyte solution is 0.1 to 5 wt %, optionally 0.2 wt % to 4 wt %. If the content of the fluorosulfonic acid salt is within a given range, battery cycle and storage performance can be improved while relatively low battery resistance can be considered.

In some embodiments, the additive further includes an organic compound film-forming additive and an inorganic salt film-forming additive, wherein the organic compound film-forming additive is at least one of carbonic acid esters, sulfuric acid esters, sulfonic acid esters, phosphoric acid esters, boric acid esters, anhydrides, and inorganic salt film-forming additives. The additive is at least one of MDFOB (difluoro(oxalate)borate), MPO2F2 (difluorophosphate), MDFOP (difluorobis(oxalate)phosphate), MDFOP (difluorobisoxalate), Typically, it may be lithium difluoro(oxalate)borate, lithium difluorophosphate, lithium difluorobis(oxalate)phosphate, lithium difluorobis oxalate and the like. The addition of other additives such as fluorine salts can suppress the oxidation and reduction reactions of the electrolyte at high voltage and further reduce the increase in the anode and cathode interface resistance.

[Method of manufacturing secondary battery]

The implementation method of the present application further provides a method for manufacturing a secondary battery. The manufacturing method is

Preparing an electrolyte solution - the electrolyte solution includes an electrolyte salt and an additive, the concentration of the electrolyte salt is greater than or equal to 1.4 mol/L, and the additive includes MSO3F (fluorosulfonate), where M is Li+, Na+, At least one of K+, Rb+, Cs+ is selected - ; and injecting an electrolyte solution into the battery to proceed with formation.

In some embodiments, a method of manufacturing a secondary battery includes preparing a first electrolyte solution and a second electrolyte solution, respectively, wherein the first electrolyte solution includes a first electrolyte salt and a fluorosulfonate salt additive, and the concentration of the first electrolyte salt is 0.8 to 2 mol/L, the second electrolyte contains a second electrolyte salt, and the concentration of the second electrolyte salt is greater than or equal to 2 mol/L. First, the first electrolyte is injected into the battery, the first conversion is performed, and then the second electrolyte is injected into the battery after the first conversion to perform cycle charging and discharging.

Through in-depth research, the inventors have found that when the electrolyte salt concentration is similar in the electrolyte solution, the impregnation rate is better when injected twice than when injected once. First, if a first electrolyte containing a fluorosulfonate additive and a relatively low concentration of the first electrolyte lithium salt is injected to proceed with conversion, a relatively high charging rate can be used, and the conversion time can be reduced to improve production efficiency. . Next, a second electrolyte solution with a relatively high concentration is added to ensure less decomposition at high voltage, and its unique solvation structure can improve the oxidation resistance performance of the battery and prevent corrosion of the current collector.

In some embodiments, the mass of the fluorosulfonate in the first electrolyte solution is 0.1 to 5 wt%, optionally 0.2 wt% to 4 wt%. If the fluorosulfonate content is too low, the cycle performance of the battery at high voltage is not significantly improved, and if the fluorosulfonate content is too high, the cell resistance is not completely consumed when forming an SEI film during conversion of the battery, resulting in an increase in battery resistance, The cycle and storage performance of the secondary battery is deteriorated, and the conductivity of the electrolyte is deteriorated, so that lithium precipitation easily occurs during the cycle process.

In some implementations, as the first electrolyte salt and the second electrolyte salt, each independently one or more of (My+)x/y R1(SO2N)xSO2R2, LiPF6, LiBF4, LiBOB, LiAsF6, LiCF3SO3, LiFSI, LiTFSI, and LiClO4. selected, wherein R1 and R2 each independently represent a fluorine atom, a fluoroalkyl group having 1 to 20 carbon atoms, a fluoroalkoxy group having 1 to 20 carbon atoms, or an alkyl group having 1 to 20 carbon atoms, x is an integer from 1 to 3. In some embodiments, LiFSI, LiPF6, LiTFSI, LiCF3SO2NSO2F.

In some implementations, the second electrolyte further comprises an organic film-forming additive, wherein the organic film-forming additive is one or more of a carbonic acid ester, a sulfuric acid ester, a sulfonic acid ester, a phosphoric acid ester, a boric acid ester, and an anhydride. When an organic film-forming additive is added, a film can be formed on the surface of the anode or cathode, reducing oxidative decomposition of the solvent on the surface of the electrode.

[Anode plate]

A positive electrode plate generally includes a positive electrode current collector and a positive electrode film layer provided on at least one surface of the positive electrode current collector, and the positive electrode film layer contains a positive electrode active material.

As an example, the positive electrode current collector has two opposing surfaces in its thickness direction, and the positive electrode film layer is provided on any one or both surfaces of the two opposing surfaces of the positive electrode current collector.

In some embodiments, a metal foil or a composite current collector may be used as the positive current collector. For example, aluminum foil can be used as the metal foil. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector is a metal material (aluminum, aluminum) on a polymer material substrate (polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.) alloys, nickel, nickel alloys, titanium, titanium alloys, silver and silver alloys, etc.).

In some embodiments, a cathode active material for a battery known in the art may be used as the cathode active material. As an example, the cathode active material may include at least one of a lithium-containing phosphate having an olivine structure, a lithium transition metal oxide, and each of these modified compounds. The present application is not limited to these materials, and other conventional materials that can be used as a positive electrode active material for a battery may also be used. These cathode active materials may be used alone or in combination of two or more. Here, examples of the lithium transition metal oxide include lithium cobalt oxide (e.g. LiCoO2), lithium nickel oxide (e.g. LiNiO2), lithium manganese oxide (e.g. LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel Manganese oxide, lithium nickel cobalt manganese oxide, such as LiNi1/3Co1/3Mn1/3O2 (abbreviated as NCM333), LiNi0.5Co0.2Mn0.3O2 (abbreviated as NCM523), LiNi0.5Co0.25Mn0.25O2 (abbreviated as NCM211), At least one of LiNi0.6Co0.2Mn0.2O2 (abbreviated as NCM622), LiNi0.8Co0.1Mn0.1O2 (abbreviated as NCM811), lithium nickel cobalt aluminum oxide (e.g. LiNi0.85Co0.15Al0.05O2) and modified compounds thereof. Examples of olivine-structured lithium phosphates include lithium iron phosphate (e.g. LiFePO4 (also referred to as LFP)), composites of lithium iron phosphate and carbon, lithium manganese phosphate (e.g. LiMnPO4), phosphoric acid It may include at least one of a composite material of lithium manganese and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon, but is not limited thereto.

In some embodiments, the anodic membrane layer may also optionally include a binder. As an example, the binder is polyvinylidene difluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoro It may include at least one of an ethene terpolymer, a tetrafluoroethene-hexafluoropropylene copolymer, and a fluoroacrylate resin.

In some embodiments, the anodic film layer may also optionally include a conductive agent. As an example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon quantum dots, carbon nanotubes, graphene, and carbon nanofibers.

In some embodiments, the positive electrode plate is formed by dispersing components for preparing the above-described positive electrode plate, such as a positive electrode active material, a conductive agent, a binder, and any other components, in a solvent (eg, N-methyl pyrrolidone) to form a positive electrode slurry; It can be obtained by applying the positive electrode slurry to the positive electrode current collector and going through processes such as drying and cold pressing.

[negative plate]

The negative plate includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, and the negative electrode film layer contains a negative electrode active material.

As an example, the negative electrode current collector has two opposing surfaces in its thickness direction, and the negative electrode film layer is disposed on any one or two of the two opposing surfaces of the negative electrode current collector.

In some embodiments, a metal foil or composite current collector may be used as the negative current collector. For example, copper foil can be adopted as the metal foil. The composite current collector may include a polymer material substrate layer and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector is a metal material (copper, copper) on a polymer material substrate (polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.) alloys, nickel, nickel alloys, titanium, titanium alloys, silver and silver alloys, etc.).

In some embodiments, an anode active material for a battery known in the art may be used as the anode active material. As an example, the negative electrode active material may include at least one of artificial graphite, natural graphite, soft carbon, hard carbon, a silicon-based material, a tin-based material, and lithium titanate. As the silicon-based material, at least one of pure silicon, a silicon-oxygen compound, a silicon-carbon composite, a silicon-nitrogen composite, and a silicon alloy may be selected. As the tin-based material, at least one of pure tin, a tin-oxygen compound, and a tin alloy may be selected. The present application is not limited to these materials, and other conventional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

In some embodiments, the cathode membrane layer may also optionally include a binder. As an example, binders include styrene butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA) and carboxymethylchitosan (CMCS).

In some embodiments, the cathode membrane layer may also optionally include a conductive agent. As an example, at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon quantum dots, carbon nanotubes, graphene, and carbon nanofibers may be selected as the conductive agent.

In some embodiments, the cathode membrane layer optionally also includes other adjuvants such as thickening agents (eg, carboxymethylcellulose sodium (CMC-Na)).

In some embodiments, the negative electrode plate is formed by dispersing the above-mentioned components for preparing the negative electrode plate, such as a negative electrode active material, a conductive agent, a binder, and any other components, in a solvent (eg, deionized water) to form a negative electrode slurry, and the negative electrode slurry is formed as a negative electrode. It can be obtained by applying to a current collector and going through a process such as drying and cold pressing.

[Separator]

In some implementations, the secondary battery further includes a separator. In the present application, the type of separator is not particularly limited, and a separator having a known porous structure having excellent chemical stability and mechanical stability may be selected.

In some embodiments, at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene difluoride may be selected as the material of the separator. The separator may be a single-layer thin film or a multi-layer composite thin film, and is not particularly limited thereto. When the separator is a multi-layer composite thin film, the materials of each layer may be the same or different, and this is not particularly limited here.

In some embodiments, the positive electrode plate, the negative electrode plate, and the separator may be manufactured as an electrode assembly through a winding process or a lamination process.

In some embodiments, the secondary battery may include an external package. The external package may be used to package the electrode assembly and the electrolyte described above.

In some embodiments, the external package of the secondary battery may be a hard shell such as a hard plastic shell, an aluminum shell, or a steel shell. The external package of the secondary battery may be a soft package such as a pouch type soft package. The material of the soft package may be plastic, and examples of the plastic may include polypropylene, polybutylene terephthalate, and polybutylene succinate.

In the present application, the shape of the secondary battery is not particularly limited, and it may be cylindrical, prismatic, or any other shape. For example, FIG. 1 shows a secondary battery 5 having a prismatic structure as an example.

In some embodiments, referring to FIG. 2 , the outer package may include a housing 51 and a cover plate 53 . Here, the housing 51 may include a bottom plate and a side plate connected to the bottom plate, and may be surrounded by the bottom plate and the side plate to form an accommodation cavity. The housing 51 has an opening communicating with the receiving cavity, and a cover plate 53 is used to cover the opening to close the receiving cavity. The positive electrode plate, the negative electrode plate, and the separator may form the electrode assembly 52 through a winding process or a lamination process. The electrode assembly 52 is packaged within the receiving cavity. The electrolyte solution is impregnated into the electrode assembly 52 . The number of electrode assemblies 52 included in the secondary battery 5 may be one or more, and a person skilled in the art may select one according to specific actual needs.

In some embodiments, the secondary battery may be assembled into a battery module, and the number of secondary batteries included in the battery module may be one or more, and a person skilled in the art may select a specific number depending on the application and capacity of the battery module.

3 is a battery module 4 as an example. Referring to FIG. 3 , in the battery module 4 , several secondary batteries 5 may be sequentially arranged along the longitudinal direction of the battery module 4 . Of course, it may be arranged in any other manner. In addition, several secondary batteries 5 may be fixed with a fixing member.

In some embodiments, the battery module 4 may further include a housing having an accommodation space in which several secondary batteries 5 are accommodated.

In some embodiments, the above-described battery modules may also be assembled into a battery pack, and the number of battery modules included in the battery pack may be one or more, and a person skilled in the art may select a specific number depending on the application and capacity of the battery pack. .

4 and 5 show the battery pack 1 as an example. Referring to FIGS. 4 and 5 , the battery pack 1 may include a battery case and several battery modules 4 disposed within the battery case. The battery case includes an upper case 2 and a lower case 3, and the upper case 2 may cover the lower case 3 to form a sealed space for accommodating the battery module 4. Several battery modules 4 may be arranged in the battery case in any manner.

In addition, the present application also provides an electrical device, and the electrical device includes at least one of a secondary battery, a battery module, or a battery pack according to the present application. A secondary battery, a battery module, or a battery pack may be used as a power source for electrical devices or as an energy storage device for electrical devices. Electric devices include mobile devices (eg mobile phones, laptops, etc.), electric vehicles (eg pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf cars, electric trucks, etc.), electric trains, It may include, but is not limited to, ships and satellites, energy storage systems, and the like.

As an electric device, a secondary battery, battery module or battery pack can be selected according to usage requirements.

6 is an electric device as an example. This electric device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. A battery pack or battery module may be used to meet the requirements of electric devices for high performance and high energy density of secondary batteries.

[Example]

Hereinafter, the present invention will be further described by combining specific examples. It should be understood that the following exemplary embodiments are used for illustrative purposes only and are not intended to limit the present invention. Unless otherwise specified, all reagents used in the examples are commercially available or synthesized according to conventional methods and can be used directly without further treatment. Experimental conditions not specified in the examples adopt conventional conditions or conditions recommended by material suppliers or equipment suppliers.

Example 1

Manufacture of positive plate

The cathode active material (NCM523), the conductive agent (acetylene black), and the binder (polyvinylidene difluoride (PVDF)) were dissolved in a solvent (N-methyl pyrrolidone (NMP)) in a weight ratio of 96.5:1.5:2 and sufficiently After stirring and mixing uniformly, a positive electrode slurry is obtained, and then the positive electrode slurry is uniformly applied to the positive electrode current collector, and then a positive electrode plate is obtained through drying, cold pressing, and slitting.

Manufacture of negative plate

Active material (artificial graphite), conductive agent (acetylene black), binder (styrene butadiene rubber (SBR)), thickener (carboxymethylcellulose sodium (CMC-Na)) in a weight ratio of 95:2:2:1, solvent (deionized water) ) and uniformly mixed with a solvent (deionized water) to obtain a negative electrode slurry, then uniformly apply the negative electrode slurry to the negative electrode current collector copper foil, dry it, obtain a negative electrode film, and again cold press and slit to obtain a negative electrode plate.

Manufacture of Electrolyte

Using EC/EMC=3/7 (mass ratio) as a solvent, adding 1% LiSO3F and then adding LiFSI so that the electrolyte salt concentration is 1 mol/L to obtain a first electrolyte solution, EC/EMC=3/7 (mass ratio) is used as a solvent and LiFSI is added so that the electrolyte salt concentration is 2.4 mol/L to obtain a second electrolyte solution.

Manufacture of Separation Membrane

A conventional polypropylene film is used as a separator.

Manufacturing of secondary batteries

An electrode assembly is obtained by stacking and winding a positive electrode plate, a separator film, and a negative electrode plate in order, and the electrode assembly is placed in an external package, dried, injected with an electrolyte solution, and then left at a high temperature, and a secondary battery is manufactured through a chemical process. Here, the step of injecting the electrolyte is as follows.

Step 1: Inject the first electrolyte solution into the secondary battery, the injection amount is 70% of the total battery injection amount, and the secondary battery is left at a high temperature and converted.

Step 2: A second electrolyte is injected into the secondary battery formed in step 1, and cycle charging and discharging of the secondary battery is performed.

Examples 2 to 14 and Comparative Examples 1 to 5

The manufacturing method is similar to Example 1, but the difference is that the corresponding secondary battery is obtained by changing the concentration of the electrolyte salt, the order of injection, the additive, and the number of injections in the manufacturing process. For details, see Table 1.

Table 1: Manufacturing related parameters of each Example and Comparative Example

The total concentration of the electrolyte salt means the concentration of the electrolyte salt of the secondary battery electrolyte prepared through the above-described steps.

test part

(1) Interfacial lithium non-precipitation magnification test after full charge

At 25°C, the secondary batteries of Examples and Comparative Examples were tested in the following manner.

1) Charge to 4.45V with xC constant current, then charge with constant voltage of 4.45V until the current is less than 0.05C, then discharge to 2.8V with xC, and cycle 10 times.

2) Charge up to 4.45V with a constant current of xC, and then charge until the current is less than 0.05C with a constant voltage of 4.45V to obtain a fully charged secondary battery.

3) Disassemble the secondary battery and observe the lithium precipitation situation on the anode.

4) The above operation is repeated until lithium is not precipitated, and the x value at which the battery does not completely precipitate lithium is taken as the fully charged lithium non-precipitation multiplier of the first electrolyte solution.

(2) 45℃ cycle performance test

At 45°C, the secondary battery is charged to 4.45V with 0.1C constant current, then charged with a constant voltage of 4.45V until the current is less than 0.05C, and then the secondary battery is discharged to 2.8V with 0.2C constant current, which is The discharge capacity C (Ah) is obtained in one charge and discharge process. By repeating the charging and discharging in this way, the number of cycles for maintaining the capacity of the secondary battery is calculated.

Table 2: Performance test corresponding to each Example and Comparative Example

According to the test results in Table 2, when the electrolyte has a concentration of electrolyte salt greater than or equal to 1.4 mol/L at the same time, MSO3F is included in the additive, and at least one of Li+, Na+, K+, Rb+, Cs+ is selected as M, The cycling performance of the battery at high voltage was greatly improved.

At the same time, through comparison between Examples 1 to 6 and Comparative Example 3, the higher the concentration of the first electrolyte salt in the first electrolyte solution, the smaller the magnification at the time of cell conversion (ie, the longer the time required for conversion) and the conversion production capacity It can be seen that the decrease affects the battery production efficiency.

Through comparison of Examples 4 and 6 and Comparative Examples 4 and 5, the injection order of the first electrolyte and the second electrolyte affects the impregnation rate of the first electrolyte into the positive electrode plate, and the second electrolyte is injected first. It can be seen that the interfacial lithium non-precipitation rate after full charging is significantly lowered, and the polarization is too large during the charging process, so only a relatively small charging rate can be used during formation, and the production efficiency of the battery is lowered due to the long conversion time.

Through a comparison between Example 8 and Example 11, it can be seen that the cycle performance of the secondary battery is further improved after adding the LiPO2F2 additive.

Through comparison between Examples 11 and 12, the first injection reduced both the impregnability of the electrolyte into the positive electrode plate and the interfacial lithium non-precipitation ratio after the first charge of the electrolyte, compared to the second injection. It can be seen that the production efficiency decreases with increasing time.

Through comparison between Example 3 and Comparative Example 4, it can be seen that the cycle performance of the secondary battery is significantly reduced when the fluorosulfonate additive is not added.

According to the disclosure and teaching of the above description, those skilled in the art may change and modify the above-described embodiment. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some modifications and changes of the present invention should also fall within the protection scope of the claims of the present invention. In addition, although some specific terms are used in this specification, these terms are only for facilitating explanation and do not constitute any limitation to the present invention.

1 - battery pack; 2 - upper case; 3 - lower case; 4-battery module; 5-secondary battery; 51 - housing; 52 - electrode assembly; 53 - cover plate.

Claims (15)

An electrolyte solution comprising an electrolyte salt and an additive, wherein the concentration of the electrolyte salt is greater than or equal to 1.4 mol/L, and the additive comprises MSO3F, wherein M is at least one of Li+, Na+, K+, Rb+, Cs+ Electrolyte, characterized in that selected. The electrolyte according to claim 1, wherein the concentration of the electrolyte salt is 1.7 to 2.9 mol/L. The method of claim 1 or 2, wherein the electrolyte salt includes one or more of (My+)x/y R1(SO2N)xSO2R2, LiPF6, LiBF4, LiBOB, LiAsF6, LiCF3SO3, LiFSI, LiTFSI and LiClO4, wherein the R1 , R2 each independently represents a fluorine atom, a fluoroalkyl group having 1 to 20 carbon atoms, a fluoroalkoxy group having 1 to 20 carbon atoms, or an alkyl group having 1 to 20 carbon atoms, and x is an integer of 1 to 3 And, optionally, the electrolyte solution characterized in that the electrolyte salt comprises one or more of LiFSI, LiTFSI, LiPF6, LiCF3SO2NSO2F. 4. The electrolytic solution according to any one of claims 1 to 3, wherein the fluorosulfonic acid salt includes at least one of LiSO3F, NaSO3F, KSO3F, CsSO3F and RbSO3F. The electrolyte solution according to any one of claims 1 to 4, wherein the mass of the fluorosulfonic acid salt in the electrolyte solution is 0.1 to 5 wt%, optionally 0.2 wt% to 4 wt%. The method according to any one of claims 1 to 5, wherein the additive further includes an organic compound film-forming additive and an inorganic salt film-forming additive, wherein the organic compound film-forming additive is a carbonic acid ester, a sulfuric acid ester, a sulfonic acid ester, a phosphoric acid ester, or a boric acid. It includes at least one of an ester and an anhydride, and the inorganic salt film forming additive includes at least one of fluorine oxalic acid borate, difluoro phosphate, difluoro bis (oxalate) phosphate, and difluoro bis oxalate. Electrolyte made of. A secondary battery comprising the electrolyte according to any one of claims 1 to 6. In the method of manufacturing a secondary battery,
Step S1 of providing an electrolyte solution - the electrolyte solution includes an electrolyte salt and an additive, the concentration of the electrolyte salt is greater than or equal to 1.4 mol/L, and the additive includes MSO3F, wherein M is Li+, Na+, K+, At least one of Rb+ and Cs+ is selected - ;
A method for manufacturing a secondary battery comprising a step S2 of injecting the electrolyte solution into the battery. According to claim 8,
In step S1, a first electrolyte and a second electrolyte are prepared, wherein the first electrolyte contains a first electrolyte salt, the concentration of the first electrolyte salt is 0.8 to 2 mol/L, and the second electrolyte is a second electrolyte vaginitis, and the concentration of the second electrolyte salt is greater than or equal to 2 mol/L;
In step S2, the first electrolyte solution is first injected into the battery, an MSO3F additive is added, and after the first conversion, the second electrolyte solution is injected into the battery again. 10. The method of claim 9, wherein the mass of the fluorosulfonic acid salt in the first electrolyte solution accounts for 0.1 to 5%, and is optionally 0.2wt% to 4wt%. The method of claim 9 or 10, wherein the first electrolyte salt and the second electrolyte salt are each independently (My+)x/y R1(SO2N)xSO2R2, LiPF6, LiBF4, LiBOB, LiAsF6, LiCF3SO3, LiFSI and At least one selected from LiClO4, wherein R1 and R2 are each independently a fluorine atom, a fluoroalkyl group having 1 to 20 carbon atoms, a fluoroalkoxy group having 1 to 20 carbon atoms, or an alkyl group having 1 to 20 carbon atoms. wherein x is an integer of 1 to 3, and optionally, the first electrolyte salt and the second electrolyte salt each independently include one or more of LiFSI, LiPF6, and LiCF SO 2 NSO 2 F. . The method of any one of claims 9 to 11, wherein the second electrolyte solution further comprises an additive, wherein the additive is an organic compound film forming additive, and the organic compound film forming additive is a carbonate ester, a sulfuric acid ester, a sulfonic acid ester, or a phosphoric acid ester. Method for producing a secondary battery, characterized in that at least one of ester, boric acid ester, anhydride. A battery module comprising a secondary battery according to claim 7 or a secondary battery obtained by the manufacturing method according to any one of claims 8 to 12. A battery pack comprising the battery module according to claim 13. An electrical device comprising at least one of a secondary battery according to claim 7, a battery module according to claim 13, or a battery pack according to claim 14.

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